Process of removing paraffin from oil-wells.



UNITED STATES PATENT OFFICE.'

GEORGE L. BALL, OF ALLEGHENY, PENNSYLVANIA.

PROCESS OF REMOVING PARAFFIN FROM OIL-WELLS;

SPECIFICATION forming part of Letters Patent No. 670,577, dated March 26, 1901.

Application filed August 11, 1900.

dent of Allegheny, inthe county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Processes of Removing Paraflin from Oil-Wells; and I do hereby declare the following to be a full, clear and exact description thereof.

My invention relates to a process of cleaning paraffin and similar deposits from oil-wells, and has for its object a process for removing such deposits which is comparatively cheap and easy of practice and which efiectively removes the paraflin or similar deposits from the side walls of the well and all parts of the well-cavity. 1

Oil-wells are formed by drilling or boring until a stratum of sand containing the oil or pay-sand, as it is called, is reached and the boring or drilling continued through said stratum and for some distance into the underlying rock or slate. In some cases the flow of oil is sufficiently large without shooting the well; but generally after boring the well must be shot, which is done by introducin g a very heavy charge of nitroglycerin therein and exploding the same, the concussion of which forms a cavity of considerable size in the stratum of pay-sand, and the detached material is then bailed out. The cavities formed thereby are of varying sizes, depending upon the character of the soil and size of charge of nitroglycerin used, and may vary from a diameter of three or four feet to ten or fifteen feet or even more. These cavities are usually very irregular in outline, crevices or fissures extending out therefrom to a considerable extent, especially when the soil is more or less rocky; The strata of oil-bearing sands generally lie at such a depth that more or less salt water oozes into the well, and in some regions lime water is present in considerablequantities. The action of these waters upon the oil after a time causes a deposit upon the walls ofthe well or well-cavity, said deposit being known as parafiin, but it is probably, more strictly speaking, saponified oil. At any rate this deposit on the walls of the well or well-cavity after a time becomes so thick that it greatly impedes the oozingof the oil into the cavity, and it has been found necessary to either remove such deposit or Serial No. 26,606. (No specimens.)

abandon the well. It has been attempted to remove this deposit in several ways. method has been by introducing into the well a rotating bar carrying'at its lower end pivoted arms having on their outer ends reamers or scrapers. said arms are projected affor being introduced into the well and by the rotation of the bar are caused to ream or scrape the walls of the well-cavity, thereby removing the deposit of paraffin. This method, however, is ineffective, for the reason that the sizes of the'cavities vary widely and the walls thereof are so irregular that the scraping-tools afiect only the projecting parts thereof. It has also been attempted to heat the oil in said chamber by means of a powerful electric current to cause the same to dissolve the paraffin deposit on the walls of One the chamber. This method, however, has not been practicalbecause of the excessive current.'necessary, the slight heating effect derived therefrom, and its decomposing action on theoil. The weight of the necessary heating coils and cables is such that in deep wells the cables will break, thereby rendering the device inoperative. It has also been proposed to heat the oil by. dropping hot bodies of metal into the same; but generally there is a considerable amount of oil in the well, and this, 'together with the long distance through which the body has to travel,cools the same to such an extent that but an inelfective amount of heat is com mu nicated to the oil in the cavity. It has also been proposed to heat the oil by intrpducing therein steam through a long pipe projecting down into the cavity; but in thiscase also the long distance through which the steam has to travel and the mass of oil through which the pipe passes cool the steam sutficiently to prevent any effective amount of overcomes the defects of the older methods; and to this end it consists in heating the oil in the well or well-cavity by means of suitable chemicals introduced therein and when the paraffin on the walls of the well or wellcavity has been dissolved then pumping or bailing out the contents of the well or wellcavity. I

As is Well known, the reaction of most chemicals produces heat, and with certain chemicals the. amount of heat produced in the reaction is very large. I avail myself of this well known principle for generating heat in the cavities of oil-wells. The chemicals suitable for this purpose are quite numerous; but I have found by extensive experiments that ordinary sulfuric acid used with caustic soda ninety-eight per cent. pure produces the greatest amount of heat. I prefer to introduce the caustic soda into the well and then introduce the sulfuric acid; but the order can ofcourse lie reversed. Three parts, by weight, of sulfuric acid to one part of caustic soda is about the proper proportion when the ordinary commercial sulfuric acid and ninety-eight per cent. pure caustic soda soda.

' cavity or well.

are. used; but this proportion will vary according to the strength or purity of the chemicals, which, as is well known, is never uniform even in difierent lots from the same manufacturer. This proportion will also vary according to quality of oil in the well. For instance, if there is present -in the oil a considerable quantity of lime water or salt water a larger proportion of the acid will be necessary in order to neutralize the caustic The well-cavity must be full of oil or the oil-bearing sand covered by oil before the chemicals are introduced, and if the oil should happen to be very low it will. be necessary to pour oil into the well until the cavity is full or the oil-bearing sand covered, but in most wells this is unnecessary. The reaction of the acidon the alkali produces a very high degree of heat, which is communicated to the oil in the cavity and raises the same to such a temperature that it acts as a solvent for the paraffin or other deposit on the walls ofthe It usually requires about three hours for the paraflin to become en- ,tirely dissolved; but this will vary, and it is 'necessaryto test the oil in the well from time to time to determine when the p'araifin is dissolved. When, dissolved, the contents of the cavity are bailed out before the same become cool, so that the paraffin cannot again become congealed. Various acids and vari- .ous alkalies may be usedas, for instance, in-

stead of caustic soda I can use carbonate of tions above specified in relation to sulfuricacid and caustic soda; but as sulfuric acidis the cheapest commonacid and as it produces ahigher degree of heat than the others in its I this propertymay be availed of incarrying outmy process.

The amount of chemicals introduced into the well will depend largely upon the sire of the well-cavity; but it is found that for the average well three hundred pounds of. sulfuric acid and one hundred pounds of canstic soda are sufficient by their reaction to raise the oil in the cavity to such a temperature thatthe same will act as a'solvent for the paraffin. The proportions of the chemicals will be so arranged that they will practically neutralize each other, thereby preventing any injurious or harmful efiect on the baileror other apparatus necessary to use.

The chemicals may be introduced into the well by dropping or pouring them therein, and as they are heavier than the oil they sink to the bottom of the well, so'that the heat" is generated .in the cavity where it is required;

but the chemicals, or at least the acids, may

too

The order in which the chemicals areintroduced into the well is, as above stated, immaterial, although I prefer to first introduce the alkali and then the acid; but this order can of course be reversed, and in some cases it may be convenient or desirable to introduce them simultaneously.

It will be readily apparent that my inven.

tion provides a method-of removing deposits from oil-wells which is practical and efiective, V

1. The method of removing paraffin and other deposits from oil-wells which consists. in introducing into the well chemicals the reaction of which on the fluid in thewell and The cost on each other will heat the oil orfinid in the well and dissolve the paraffin or other deposits.

2. The method of removing paraffin? and other deposits from oil-wells which consists in introducing into the well chemicals the reaction of which on each other will heat the oil or fluid in the well and dissolve the paraftin and then bailing out thewell before the dissolved paratfin has cooled.

The method of removing paraffin and other deposits from oil-wells which consists in introducing into the well a chemical'or chemicals and then introducing into the well another chemical the reaction of which with the first chemical will heat the oil or fluid in the well and dissolve the parafiin or other deposits.

4. The method of removing paraflin and other deposits from oil-wells which consists in introducing into the well an alkali and an acid in suitable proportions, the reaction of which will heat the oil or fluid in the well and dissolve the paraflin or other deposits.

5. The method of removing paraffin and other deposits from oil-wells which consists in introducing into the Well in succession an acid and an alkali in such proportions that F. W. WINTER, MAY MAGEE. 

